BLAST screening of chlamydial genomes to identify signature proteins that are unique for the Chlamydiales, Chlamydiaceae, Chlamydophila and Chlamydia groups of species

Table 6 Stage-specific Expression of some of Chlamydiae-specific Proteins

Stage of Expression	Chlamydiales-specific Proteins	Chlamydiaceae-specific Proteins	Chlamydia-specific Proteins	Lost or Transferred Genes
I-Early (6–24 hpi)		CT233
II-Midlate (12–24 hpi)	CT053 CT635	CT289 CT671	CT360	CT550
	CT066 CT666	CT372 CT870
	CT273 CT667	CT377 CT871
	CT504 CT670	CT413 CT872
	CT590 CT734	CT618 CT874
		CT668
III-Midlate (18–24 hpi)		CT142		CT049
		CT143		CT051
		CT681
		CT713
IV-Late (24–36 hpi)	CT016	CT005 CT552	CT249	CT050
	CT017	CT046 CT565		CT214
	CT181	CT080 CT578	CT694	CT702
	CT443	CT082 CT579
	CT546	CT083 CT620		CT868
		CT147 CT695
		CT288 CT712
		CT365 CT848
		CT392 CT869
		CT442
		CT444

The temporal expression patterns of these proteins is based upon the microarray analysis of Nicholson et al [63]. According to the microarray profiles, significant differences were seen in the expression pattern of genes for these proteins at 4 different time points (6–24 hours post infection, 12–24 h.p.i., 18–24 h.p.i., and 24–36 h.p.i.) which correspond to different phases of the chlamydial developmental cycle where key phenotypic changes take place. It is of interest that the majority of the temporally regulated Chlamydiales and Chlamydiaceae-specific genes are expressed between 12–24 h.p.i. and 24–36 h.p.i. Such coordinate regulation suggests they play essential roles during these phases of the chlamydial cell cycle. Other chlamydiae-specific proteins which are not listed in this Table were not found to show significant differences in their temporal expression in the study by Nicholson et al. [63]. Abbreviation; h.p.i., hours post infection.

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